You've stated you don't want to test the water, but the process of diagnosing a problem pretty much begins with that and knowing what the conditions of the water are. Some good test kits available online for under $20, only slightly more at your local pet store. (liquid is more accurate than strips, but strips are better then nothing).

Fish stores and pet stores that sell fish can test your water for you and/or help you learn how to do it.

Either the symptoms you are seeing are the direct cause of poor water conditions, or a lot of times diseases are caused by poor water conditions that weaken the fish and make it more susceptible to disease or parasites. Either way, you would need to fix the water conditions.

Once you've corrected the water - or if youve tested it and know it's OK - then move on to treating the disease (may have come from the shop with flukes or something.)

Once pond or tank is established you don't need to be testing all the time, maybe every couple of months if at all. But when something goes wrong, that really is the starting point for figuring it out.

Thank you for replying!
I was also thinking of putting 1-4 inch feeding fish/goldfish in the pond if this last koi won't make it. Are they easy to care for?

Should I also put this last koi in a fish tank?
It is fairly large and could fit a lot more fish.

As kashka says, you are going to be stuck doing some water testing. I believe that there are some test kits that only use test strips. They are probably more expensive per test and less accurate, but they well be convenient and well within anyone's ability. Probably the most critical issue would be evidence of Any ammonia or a pH below 5.5 (I'm guessing about that one) or above pH 9. And you didn't explain the source of your water or timing of addition which could cause problems if youu are on city water. I'm on a well so I have forgotten how careful you need to be in adding muni. water. I believe I have heard no more than 5%/day addition and I don't know how long you need to wait before adding fish if you filled the whole pond.

More info on your pond might be valuable. I like your idea of rescuing your last fish to a tank, but the water should have set for awhile or be extensively aerated. If it were me, I would do some easy test strips and if OK then would add a test comet goldfish or something and see if all appears well before adding more fish.

I did clean my pond once and did fill the whole pond because I didn't have much time :/ (I am on city water). I let it cycle for about a whole day or so, with the fountain running the entire time. The last fish seems to be doing okay, and today I pre-soaked the pellets before feeding it, and the koi did eat some of it.
I did find some pool pH test strips and the pH and alkalinity were in a good range, but these strips didn't test for ammonia levels?
The tank I was thinking of putting the last fish in would be a lot of hassle since it is pretty big for just one fish, and it is empty and below my current turtle tank on a stand. I was thinking of switching the turtles and the koi, so that the turtles were outside in the pond (I have put turtles in the pond in the past and they didn't fall sick or anything, but they did escape the pond :() and the koi would be inside that tank, but then I thought of some aeration problems??? All I have currently for my turtles are two small filters like a Reptofilter (I forgot the brand name) and I also have a small air tube that I use to use for some feeding fish. Would that be enough if I were to put my Koi in the tank? The air bubbler doesn't do much in the tank, and the filters don't make much happen on the surface of the water.
I also have a fish bowl that looks like this and would be a lot easier to use, but I'm not sure that would be enough for the koi?
I'm not sure if I really want to put my turtles outside in the pond. It broke my heart when my turtles escaped last year. Suggestions?

This post was edited by l025 on Fri, Jun 21, 13 at 13:49

Did you treat the water before putting the fish in? If your city uses choloramines, it actually will break down into ammonia, so it takes much longer for the water to become safe if you don't treat it first.

I just treated the water with some algae control, and left it there with the pump on for a day or so i think.
But I don't think that has much to do with the dead fish because when I first filled the pond before putting any fish in, I left it there for like a week.

I just treated the water with some algae control, and left it there with the pump on for a day or so i think.
But I don't think that has much to do with the dead fish because when I first filled the pond before putting any fish in, I left it there for like a week.

Sounds to me like your water is toxic. I know chlorine is bad for city fish, and it is important to add a de-chlorinator for that. Also, may you could put some kind of basket over the intake on your fountain.
Definately get a water testing kit if you have fish. It might seem like a small expense, but in order to keep fish, it is necesssary to know water parameters.
I got one off of amazon for around 25 bucks. Mine was reccomended by many aquarium fish keepers. It is call API Freshwater Master Test Kit. Also about the salt... I hope you measured correctly for the gallons in your pond. It is better to undermeasure the salt, than to overdose. I use Celtic Sea Salt and my fish do well.
One other thing... Fish are sensitive to quick pH changes. If you had a test kit, you could check what the pH was in their original home vs. your own water. Some people acclimate new fish by dripping their water slowly over time into the water the new fish came in.

Don't put the koi in the fishbowl. Depending on it's size, it may be suitable for the turtles.

The turtles have been in the pond before, but I don't feel confortable with it

The turtles have been in the pond before, but I don't feel confortable with it

"I am a beginner ponder, so testing the water and adding different liquid solutions probably won't work with me..."

Bottom line, to keep koi you need to provide them with as pristine water as possible. City water is not anywhere near that in most situations as pointed out above. City water is treated with chemicals to make it drinkable. Chlorine and chloramines kill bad bacteria and koi too. You will also need some sort of filtration to keep that water clean and to remove solids and ammonia.

If you still are not interested in the complications of koi keeping why not consider goldfish or comets? You have a pretty good set up for them. Add a bunch of plants. Let your water set with the fountain going for about a week or so and then add a small "feeder" type gold fish. If it lives, add more. Just a few at a time so that they can get your bacteria cycled.
Get a bottle of pond chlorine/chloramine remover and every time you have to add water, estimate how much you are adding and add the correct amount of remover at the same time. Best actually to mix it before hand in a bucket. Even for goldies, I'd add a filter but if that is not possible, increase your plants and do water changes like you would an aquarium.

Well currently there's a filter, but it just filters large objects like leaves and stuff...
I was going to add some small goldfish when I'm near a pet store.
My last koi is doing fine, but since it's still pretty new, it hides all day but occasionally comes out to swim (no flashing or anything, so I'm glad)
I will probably get some pond chlorine that you are talking about whenever, again, I am near a pet store.
The pond has like fake lily pads and a real plant.

The fish may have arrived with some sort of problem. When I first started out, I bought koi, cheap, at Pet Stores and I'd always lose some. Had to replace them last year due to a mechanical problem. I went to an Aquarium Shop and paid $5-$7 for 3 or 4 inch koi. All of them survived, still doing well and growing strong.

I got mine from dog patch, and they were baby koi that were about three inches and were 2 dollars each... The people there said they rarely have to pick out dead kois from that quarantine, but they could be just saying that?
The last koi is doing fine, and since I began presoaking the pellets I found that it didn't feel comfortable eating at the surface of the pond yet, so I have begun squishing them so they would sink and I can make sure it eats.